Re: GBlist: re: concrete houses

Norbert Senf (
Tue, 25 Feb 1997 08:29:29 -0400

Buzz Burrell wrote:

> The simple wall I envision: 6" thick concrete, with 3" of rigid board on
> the exterior, rendered with the normal (for out here) 3 coats of
> cementitious stucco. Plaster inside. Walls and corners are easily
> sculpted for the adobe look, mediterranean, spanish, or anything desired.
> After rendering, you couldn't tell what it was made of.
> In our climate, thermal mass is a big plus, and so is a stuccoed
> exterior, both for practical and stylistic considerations. Thus, here
> are some of the advantages of this concrete wall system, specific to my
> own circumstances and my location:

Hi Buzz:

We built our house in '81, and it is constructed of 6" hollow cmu with
4" of blue SM foam (blown with freon, no doubt) on the outside (covered
with stucco) and traditional lime-sand plaster on the inside. At the
time, we were off-grid (back then it was called "not having any
electricity"), so our main consideration was being able to leave the
house for a few days without backup heat and not having it freeze in our
8800 degree-day climate. It works wonderfully in that respect. We let
our wood-fired cookstove go out at night, and in the morning when you
wake up, you have no way to tell what the temperature is outside without
looking at a thermometer (or standing close to a window).

The advantage of the c.m.u.'s for us was that there was no formwork,
plus I used to set them for a living, so they went up very fast. Might
be less e.e. too, but not sure. Certainly, it is plenty of mass. If you
let the house get cold, it takes about a day to get it back up, and I
wouldn't want it to take any longer than that.

If we had wanted to get fancy, we could have drawn air from the peak of
the house to the basement through the cores of the blocks in the North
wall. In our sunspace, there is an air-core floor consisting simply of
8" cmus laid on their sides with the cores lining up, onto foam, with a
1" topping of mesh-mortar-tile. There is a header at either end, so the
cores run in parallel. We've never hooked it up, because the house can
absorb any extra heat without problem. In the summer, we can run our
cookstove for breakfast most days, and again the house can easily absorb
the heat.

Summer cooling is a non-issue at this latitute - even with 90+ degree
daytime temperatures, you can count the really warm nights with the
fingers of one hand. Our primary consideration in siting the house was
to have a large deciduous shade tree to the south, and that's all you
need to do up here if, in addition, you have the thermal mass to
transfer "coolth" from night to day.

Norbert Senf email:
Masonry Stove Builders
RR 5, Shawville website:
Quebec J0X 2Y0 fax: 819.647.6082
voice: 819.647.5092
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